RICHLAND CREEK CASE STUDY RICHLAND CREEK WATERSHED DESCRIPTION The Richland Creek watershed drains 1254 km2 (488 mi2) in the Highland Rim and Central Basin regions of Tennessee. Underlain primarily with limestone, gently rolling and steep-sided hills constitute much of the surficial topography. Woodlands, which cover approximately 37% of the watershed area, are restricted mainly to the headwater regions of the watershed. Agricultural land accounts for nearly 60% of the watershed area and supports corn, soybean, tobacco, cotton, livestock and dairy production operations. Municipalities, small factories, warehouses and a solid waste treatment are are found on land designated as urban. This land, located mainly in the city of Pulaski, makes up approximately 3% of the watershed area. Richland Creek mainstream discharge reached a maximum of 37,700 cubic feet per second in 1974, and a minimum of 8.2 cubic feet per second in 1953. Mean annual discharge ranged between 217 cubic feet per second and 1,133 cubic feet per second; the annual minimum three-day mean discharge for a 20-year recurrence interval (3Q20), approximated 12 cubic feet per second. The quality of Richland Creek and its tributaries are influenced by agricultural and urban runoff. Thirteen NPDES permits have been issued for storm water discharge purposes, and six have been issued for daily maximum loads. Surface water withdrawals and outflows are primarily located in the vicinity of Pulaski. Average daily withdrawals are approximately 3,200,000 gallons per day. Instream water quality surveys in the watershed, conducted by local, state, and federal agencies, have been spatially and temporally sporadic. For example, an EPA Storet database provided monthly water quality data from October 1975 through September 1976. Water temperatures in the Richland Creek mainstem ranged from 6.1-24.4 oC with dissolved oxygen levels between 9 and 12 milligrams per liter. Richland Creek exhibited neutral pH values throughout the year.